Color photographic material and method of using the same



June 8, 1943. P. GOLDFINGER 2,321,195 COLOR PHOTQGRARHIC MATERIAL AND METHOD OF USING THE SAME Filed Dec. 4, .1939

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, 3mm Paul aoldjz' g n Patented June 8, 1943 COLOR -PHOTOGRAPHIC MATERIAL AND METHOD OF USING THE SAME Paul Goldiinger, Brussels-,Uccle, Belgium, assignor, by mesne assignments, to Chromo'gen, Incorporated, a corporation Nevada Application December 4, 1939, Serial No. 307,50?

In Great Britain December 22, 1938 12 Claims In many of the known processes, photographic dye pictures are obtained by exposing a layer of light-sensitive silver halide emulsion and converting the latent images thus produced, or the silver im'ages formed by developing, or even the unexposed silver halide that has been unaffected by the developing process into a dye picture. It

is desirable and-necessary in every instance in order to ensure the greatest fidelity in the reproduction of the objects photographed, that the graduations of the dye picture subsequently obtained correspond as far as possible with the graduations of light 1. e., range of light intensities originally recorded in the silver halide emulsion during the exposure.

- It has, however, been found that generally the hues of the dye picture correspond to the graduations of light or range of lightintensities recorded during the exposure toonly a limited extent and that, for instance, when a silver image in which there are 15 graduations of silver densities is processed to obtain a dye picture, there are guished in the latter; the densest graduations in the silver image are not reproduced by distinctgreatest without regard 'to the different graduations of the silver deposit and thus the graduabut 8 graduations of hue to be clearly distintions of the darkest areas are not reproduced by stood from the following description of specific Y embodiments when read in connection with the accompanying drawing, in which like reference characters indicate likeparts throughout.

Fig. 1 is a diagrammatic view in cross-section of a diffusely dyed layer which has been exposed and the silver image developed;

Fig. 2 is a diagrammatic view in cross-section of the layer shown in Fig. 1 after the silver image has been transposed toa dye image; v

Fig. 3 is a diagrammatic view in cross-section of a layer similar to that shown in Fig. 2 containing a dye image of greater detail than that in Fig. 2;

Fig. 4 is a diagrammatic view in cross-section of a two-layer element comprising layers of the type shown in Figs. 1 and '3, both of which layers have been diffusely dyed the same color and have been exposed and the silver images developed;

Fig.'5is. a diagrammatic view in cross-section of the two layers shown in Fig. 4 after the silver 'images have been transposedinto dye images.

The undesired behaviour of photographic silver halide layers during the transformation into dye images and the manner in which it canbe 'compensated for, are graphically illustrated in-the attached drawing which refers to the above case where the dye images are obtained by local destruction of the dyes at the silver areas. Fig. 1 represents a photographic layer known in the prior art that is uniformly colored as indicated by horizontal hatching and contains a silver image of graded density, variations of the densitybeing illustrated schematically by the vertically hatched steps in the-drawing.

.Fig. 2 employs the same graphical method to show the dye image left in such a prior art layer after the dye has been destroyed where silver was present, the silver being eliminated from the picture. The graduations recorded during the exposure and shown in Fig. 1 extend over a wide range but the dye image represented in Fig. 2 reproduces but a portion of these graduations. Fig. 3 illustrates graphically dye images obtained by other methods or under other processing conditions from silver pictures of the type illustrated. in Fig. 1.

In every case it is observed that the graduations of the dye image do not exactly reproduce the graduations of the original silver the range of lightintensities originally recorded during the exposure. The principle upon which the invention is based is graphically illustrated in Fig. 4 in the same manner as employed in Figs. 1 to 3. Fig. 4 shows two light-sensitized layers of which layer A consists of a silver halide emulsion of the. same nature as that in Fig. 1

and thus records the gradations of the exposure in the same manner. Layer Bis immediately adjacent to layer -A and in respect to the coloring both layers are substantially identical, the dye. I

in layer B being employed in obtaining a color picture just as is the case with the dye in layer'A. Layer B is alsosubstantially identical with layer A in respect to thespectral sensitivity as both are intended to record the same color of the object. The only difference between the two layers is that layer B is considerably less sensitive than layer A, the result being that while layer A records a broad range of light intensities, layer B records only the highest lights. This characteristic of layer B is illustrated in Fig. ,4 which shows that only the greatest intensities of .light recorded in layer A are also recorded in layer B.

transformation into a dye image, is recorded by layer B in the form of 'a silver deposit of such lower densities that an image-like graduation of the dye is obtainable. Thus the details lacking in layer A appear as a dye image in layer B and both layers together reproduce the full range of the recorded light intensities.

The invention above described in principle may be realized in practice as illustrated in the following example:

Two silver halide layers, one of which consists of a highly sensitive panchromatic emulsion (sensitivity 28 Sch) while the other consists of an emulsion with a sensitivity of about 13 Sch, are coated in, superposition on a support. Both emulsions are colored with 0.4 grm. per sq. m. Benzopurpurine 10B (Schultz Farbstofitabellen, Leipzig 1931, 7th ed., vol. 1, No. 489).

After exposure under a-graduated'wedge, the steps of which differ in density by 0.2 in logarithmic units and after treatment in a bath containing 5% hydrochloric acid, 15% sodium chloride and 0.01% 2-amino-3-oxyphenazine sulphonic acid, the highly sensitized emulsion layer yields a color picture the threshold of which corresponds with that of the silver image, but in which nevertheless only the lower 7 or 8 graduatlons of light are reproduced instead of the 15 steps recorded in the form of silver.

There are, however, a further '7 or 8 graduations reproduced in color by the less sensitive layer and thus the dye images in the two layers together reproduce the total scale recorded during exposure.

The double-layer of red-dyed emulsion may form a component of a multilayer material in which the other layers may also consist of double layers. For instance, the red-dyed double-layer described above may have superposed on it another double-layer composed, according to the principles outlined above, of a highly sensitive and aless sensitive orthochromatic emulsion each containing 0.6 grm. per sq. m. Chrysophenine G (Schultz l. c., No. 726) A surface layer in front of the two composite layers may be formed of an ordinary blue-sensitive emulsion that if required may be dyed after exposure.

In many cases it is preferable to have the layer of the less sensitive emulsion arranged nearer the source of light than the more highly sensitized layer of the same color. This is an advantage in certain circumstances, as instanced in the example cited above and in which there is a blue-sensitive layer in front of the double layer dyed yellow by Chrysophenine. In certain circumstances and especially when the absorption ofthe yellow dye present in the inner layer is not too great, the blue light rays recorded in the blues-sensitive layer may penetrate into the yellow layer and produce a latent image therein that really ought only to be recorded in the blue-sensitive layer.

that is first hit by the blue light rays is not formed of the highly sensitive emulsion but rather of the emulsion with a relatively low sensitivity and which moreover is screened against blue light by the yellow dye.

Another advantage of the invention, independentof the relative position of thetwo layers,

may be achieved by the invention when different dyes of approximately the same shade are employed to dye the two parts of the composite layer. It is well known that various requirements must be taken into consideration when choosing the dyes suitable for the composition of a color photograph, for instance, care must be taken that the dye does not affect the sensitivity too much, that it does not adversely affect the sensitizer, that it is or may be fixed in the layer so that it does not wash out or difiuse. These considerations often result in the dye not having the shade that would be the most suitable ior the production of a color photograph or for its behaviour when used as a master image in a further printing operation. In the event of the dye in the highly sensitive layer not being perfectly adequate in respect to its absorption, it is possible to introduce a dye of similar shade into the less sensitive layer that, howevenhas better absorption properties than the dye in the highly sensitive layer. The total absorption of the double layer is then the sum of the absorption of the two layers and better satisfies the demand for a faithful color reproduction or for good printing characteristics of the color photograph. Thus, for example, instead of coloring each emulsion with 0.4 gm. per sq. m. Benzopurpurine 103, only the highly sensitive emulsion is colored in this manner, whereas the emulsion of lower sensitivity is colored by means of 0.4 grm. per sq. m. -T'uchechtrot 3B (Schultz Farbstofitabellen, Leipzig 1932, 7th ed., vol. 2, page 222). The total absorption of both layers together for light of the wave length 510 lis equal in both cases, whereas for light of the wave length 410 pp. 'Iuchechtrot 313 has a lower absorption than Benzopurpurine 10B and the sum of both absorptions is smaller than would be the case if if both layers were dyed by Benzopurpurine 103.

What is claimed is:

1. Alight-sensitive photographic material for the production of colored images which comprises two superposed silver halide emulsion layers, each of said layers having evenly distributed therein a coloring, substance adapted to produce colored images of approximately the same color in both layers, both layers being sensitized to and transmittant for light of the same spectral composition, the one of said layers having a 001m 'paratively low speed with respect to the other layer.

2. A light-sensitive photographic material for the production of color images which comprises It is therefore advantageous if the surface of the yellow-dyed layer with respect to theother layer, the said dyes i being resistant to ordinary photographic treating solutions and capable of being bleached with the aid of metallic silver. a

3. A light-sensitive photographic material'for the production of color images whichcomprises two superposed silver halide emulsion layers, both layers being sensitized to and transmittant for light of the same spectral composition, the one of said layers having a comparatively low speed with respect to the other layer, and both layers and transmittant for light of the same spectral composition, one of said layers being adapted to initiallyreceive an optical image and having a comparatively low speed with respect to the other of said layers which is adapted to secondarily receive the optical image. i

5. Alight sensitive photographic material for theproduction of colored images which comprises two superposed silver-halide emulsion layers, both layers being sensitized to and transmittant for light of the same spectral composition, one of said layers having a comparatively low speed with respect to the other layer, each of said layers being dyed with dyes having difi'erent character- -istics to that of the other layer but adapted to render substantially the same color, said dyes being resistant to ordinary photographic treat- Y ing solutions and capable of being destroyed in the presence of metallic silver.

6. A photographic film comprising a transparent support, a fast light-sensitive silver-halide emulsion layer thereon, and a relatively slow in which a photographic record produced within a light sensitive emulsion and representing said range of different light intensities is transformed to a colored image which reproduces in color a limited portion only of said range of diiferent light intensities which comprises forming in an emulsion layer sensitive to light of a predetermined spectral range a photographic record representing the desired rangeof different: light intensities of the'image field, forming inanother superposed emulsion layer sensitive to'. light of the same spectral range a registering photographic record of said image field while restricting the response of said layer predominantly to a range of light intensities lost in the transformation of the photographic record in said first mentioned'layer to a colored image by said coloring process, and transforming both of said photographic records into images of substantially the same color by said coloring process, whereby the range of light intensities reproduced in color in said first mentioned layer is supplemented by the 7 range of light intensities reproduced in color in said superposed layer.

8. The method of producing a colored photograph of adesired range of different light intensities of an image field by a coloring process in which a photographic record produced. within a light sensitive emulsion and representing said 1 range of different light intensities is transformed I to a colored image which reproduces'in color a limited portion onlyv of said range of different light intensities, which comprises forming in an emulsion layer sensitive to light; of a'predetermined spectral range a photographic record representing the desired range of difierent light intensities of the image field, forming in a slower. superposed emulsion layer sensitive to light of the same spectral range a registering photographic record representing predominantly those intensities of said image field that are not reproduced in color by the transformation of the record in said first mentioned layer to a colored image by said coloring process, and transforming both of said photographic records into images of substantialiy the same color by said coloring'process.

9. The method of producing a colored photograph of'a desired range of different light intensities of an image field by a coloring process in which a photographic silver image produced within a difiusely dyed light sensitive emulsion and representing said range of different light intensities is transformed to a colored image by local destruction of the dye at, the places where silver is present, which comprises forming in a diffusely dyed emulsion layer sensitive to light of a predetermined spectral range a photographic silver image representing the desired range of different light intensities of the image field, form- 'ing in another superposed emulsion layer sensitive to light oi the same spectraivrange and diffusely dyed with a dye of substantially the same color a registering photographic silver image of the same image field representing predominantly those light intensities of the image field that are recorded by the most opaque areas of the silver image in said first mentioned layer, treating both silver images simultaneously with a dye-destroying bath which is capable of destroylng said dye locally with the aid of metallic silver, and removing the silver from the layers. I

10. The method of producing a colored photograph of a desired range of diiferent light in-' tensities of an image field by a coloring process 7 in which a photographic silver image produced within a diffusely dyed light sensitive emulsion and representing said range of diflerent light intensities-is transformed to a colored image by a predetermined spectral range a photographic silver image. representing the desired range of different light intensities of the image field, form- -ing in another superposed emulsion layer sensitive tolight of the same spectral range and diffusely dyed with the same dye as said first men- I tionedlayer a registering photographic silver image of the same image-field representing predominantly those light intensities of 'theimage field that are recorded by the most opaque areas of the silver image in said first mentioned layer,

treating both silver images simultaneously with a dye-destroying bath which is capable of destroying said dye locally with the aid of metallic silver, and removing the silver from the layers.

11. The method of producing a colored photograph correctly. representing a desired range of Mount light intensities which comprises; re-

cording an image representing a predetermined spectral range of an-image field within a lightsensitivesilver halide emulsion layer, recording -a second image of the same image field representing the same spectral range within a second light-sensitive silver halide emulsion layer that is relatively i'aster than said first mentioned emulsion layer, developing silver images within said layers, and" treating said layers to transpose said silver images into colored images of substantially the same color, said process includingthe combining of the colored image within said second layer in superposition and registry with the colored image in said first mentioned layer to correct for disproportional transition from silrespect to the other one 'verto color of the .desired range of. different light intensities represented by the silver image in said first mentioned layer.

12. A light sensitive photographic material for the production of colored images'which comprises at least three superposed silver halide emulsion layers two 'of said layers located behind a third layer having evenly distributed therein a dye- I 

